The present invention relates to improvements in apparatus for testing cigarettes and analogous rod-shaped articles of the tobacco processing industry. More particularly, the invention relates to improvements in apparatus of the type wherein rod-shaped articles of the tobacco processing industry are conveyed sideways (i.e., at right angles to their respective axes) toward, past and beyond a testing station at which their tubular wrappers are tested by one or more streams of air or another gaseous testing fluid.
Commonly owned U.S. Pat. No. 3,948,084, granted Apr. 6, 1976 to Heitmann et al., discloses a testing apparatus for cigarettes or like rod-shaped articles wherein the end faces of articles which approach the testing station are engaged by apertured sealing elements which serve to seal the end faces from the surrounding atmosphere as well as to provide paths for the admission of testing fluid into the respective ends of the wrappers. The sealing elements consist of rubber or a similar elastomeric material and are mounted on two carriers in the form of wobble plates which flank the drum-shaped conveyor for the articles and rotate therewith so that the sealing elements of the two carriers are in register with the adjacent ends of articles in the respective flutes at the periphery of the conveyor.
It is further known to provide specially designed means for ensuring that the sealing elements on the carriers of the testing apparatus will more reliably engage the adjacent ends of the articles to prevent uncontrolled leakage of testing fluid which could lead to distorted measurements and expulsion of satisfactory articles from the path wherein satisfactory articles are supposed to advance to storage, to a further processing station (e.g., into a filter tipping machine) or directly to a packing machine. Reliable sealing of the ends of articles at the testing station (so as to prevent uncontrolled escape of testing fluid) is especially desirable when the apparatus is used for the testing of filter cigarettes or filter rod sections having so-called climatic or ventilation zones with perforations which are supposed to admit predetermined quantities of cool atmospheric air into the column of tobacco smoke. The testing apparatus are supposed to monitor the permeability of such ventilation zones and to ensure segregation of all articles whose perforations admit excessive or insufficient quantities of air. Adequate sealing of the ends of cigarettes or filter rod sections against uncontrolled escape of testing fluid or uncontrolled penetration of atmospheric air is indispensable in connection with the testing of ventilation zones because even minor leaks are likely to greatly distort the results of measurements since the rate of flow of testing fluid through the perforations of a ventilation zone is very low.
A drawback of presently known testing apparatus wherein the sealing elements are forced into sealing engagement with the adjacent ends of the articles to be tested is that the complexity and cost of such apparatus are very high and also that the sealing action is not sufficiently reliable. For example, certain presently known apparatus employ axially shiftable sleeves which are slipped onto the sealing elements at or slightly ahead of the testing station. It was also proposed to move the sealing elements into engagement with the adjacent ends of rod-shaped articles by streams of air or another gaseous fluid. The provision of such devices in a testing apparatus for cigarettes or other rod-shaped articles of the tobacco processing industry contributes significantly to the initial and maintenance cost as well as to the bulk of the testing apparatus without, however, ensuring a highly predictable, reliable and reproducible sealing action.